There is known an audio signal processing system that can separate an inharmonic-structure signal component such as from drums, for example, contained in a musical audio signal (hereinafter simply referred to as “audio signal”) output from a speaker to independently increase and reduce the volume of a sound produced on the basis of the inharmonic-structure signal component without influencing other signal components (see Patent Document 1, for example).
The conventional system exclusively addresses inharmonic-structure signals contained in an audio signal. Therefore, the conventional system cannot separate “sound mixtures containing both harmonic-structure and inharmonic-structure signal components” according to respective instrument sounds.
There have been found no reports of a sound source separation technique that uses a model (hereinafter referred to as “harmonic/inharmonic mixture model”) that handles a model representing a harmonic structure (hereinafter referred to as “harmonic model”) and a model representing an inharmonic structure (hereinafter referred to as “inharmonic model”) at the same time.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-5807